University of Colorado
University of Colorado: Core Conflict Problems and Negotiation
Site contains a wealth of information on conflict, negotiation, interpersonal relationships, communication, and more. Spends considerable time with "complicating factors" in communication.
Other
Work 911: Basic Negotiating Tips
Site provides an excellent article, including an overview to the concept of negotiation, barriers to negotiation, and several useful tips for how to successfully negotiate. SL.9-10.1d Possitive Communication Stratagies